Finding 40% volume increase with no significant capex investment is a huge ask for any company, even for the proverbial godfather of lean. Toyota Deeside explains how it did it.
In 2011 the world’s best selling carmaker needed to reconfigure its global engine production to accommodate a new design, a hybrid engine for the Auris Sports Tourer. Toyota Motor Manufacturing UK’s engine plant in Deeside was asked to ramp up capacity. In addition, it won the contract to make engines for the new Corolla sedan model.
Director of the engine manufacturing division at Toyota Deeside, Richard Kenworthy, was given a serious test; find up to 40% more capacity with no substantial additional capital investment.
Toyota Deeside makes three engine variants: valvematic, non-valvematic and the new hybrid engine, in 1.6L and 1.8L sizes which are supplied to Toyota factories in Burnaston, Turkey, Brazil and Japan. Production volume in 2011 and 2012 was around 160,000-165,000 units and Toyota Group wanted to lift that to 250,000 units per year, or nearly 35%. The question was whether this was possible by optimising current processes or if capex was necessary.
To hit 250,000 without altering its two shifts, five days a week system, Deeside would need to reduce engine assembly takt time from 84 secs to 48 secs, a whopping 43% reduction. To deliver the new volume, 100 new staff were hired from November last year.
In late 2011, Deeside appointed a dedicated team of five members who led the exercise over about 12-months. The plant has multiple lines but one assembly line. The team did a proof of concept on the engine block line over six months. The plan was to stagger ramp-up to get each line operating at 54-seconds cycle time first before then shaving a further six seconds off to reach the 48-secs Holy Grail. “We proved the concept and through 2012 we extended the methods to five other machining lines to get those beneath 48-secs,” says Richard Kenworthy, a Toyota man for 21-years. This was extended to the full assembly line in Q1 2013.
“Originally we didn’t think the requirement was needed for assembly because part of our business is shipping machined components to Brazil, therefore we’re always looking for extra capacity on casting and machine lines more than assembly,” Mr Kenworthy adds. “But as year-end 2012 approached, we saw a big increase in demand for the hybrid across Europe, meaning we’d need to run it on the assembly line as well.”
Toyota is already famously lean, having pioneered the original lean manufacturing system – the Toyota Production System – in the 1950s, 60s and 70s. How could such a lean manufacturing process find such large cycle time reductions?
The project team made 455 separate modifications to the plant’s machines to reduce cycle time. “It’s like British Cycling,” says Mr Kenworthy, “a cumulative aggregation of a series of small improvements. Put altogether you can get several seconds per cycle time.”
Deeside collaborated with other divisions to find the specific alterations to realise the efficiencies. Kentucky in the US, especially, was a close collaborator. The project team spent several days in Kentucky examining specific time-saving techniques, and a US delegation has since visited Deeside. Is such cross-pollination common within Toyota? “It’s not a well-trodden path, because each site circumstances are different, but TMC [Toyota Group] head office is very keen to benchmark for regional cooperation,” says Kenworthy.
Dwell times within the assembly processes were studied and teased apart. Robotics and automating machines were assessed and, where practicable, accelerated.
Tiny improvements have been made across casting, machining and assembly. On grinding crankshafts, for example, “When the grinding wheel approaches the crankshaft at high speed, it was starting to decelerate 25mm away from the shaft. We asked if it should slow down just 5mm before it starts to approach the shaft,” Kenworthy says, emphasising the devil in the detail.
“The US guys have taken this [new technique] back and they have in effect kaizened their own kaizen.”
Elsewhere, the transfer bar on an assembly process used to drop 150mm and go under the line’s process doors. “We put a slot in all the doors, now they drop just 15mm which means it takes less time to transfer the part.”
Zone effect: Deeside has done a lot work on the “zone effect” = tool change frequency and tool change time.
For example, the cycle time on one machine is 48 secs. If the tool is changed every 1,000 operations, and it takes 10 mins (600 secs) to change that tool, the effective cycle time is 48secs + (600 / 1000 =) 0.6sec = 48.6 secs.
“A lot of these NC machines have up to six tools on them, an extra 3.6 secs on every machine,” says Kenworthy. “If engineering can reduce that to 5,000 operations then the effect on line capacity is enormous. And it’s all free.”
Deeside’s 12-month ramp-up exercise has re-emphasised the principle that there is waste hidden in everything. “They’ve had to demonstrate that they really understand what lean means. By studying the machines and studying them again they have really understood where the cycle time comes from,” says Kenworthy.
Deeside began running the casting and machining lines at 48-secs cycle time in February and March. The big test is yet to come: the assembly line will switch to 48-secs on April 22. “There’s a little nervousness but we’re confident we done enough preparation to hit the target,” Kenworthy adds.
Kaizening a kaizen: Electrical testers
To use an electrical tester at Deeside, hitherto a member would fit a harness, it would go onto the machine, which would connect to the pallet, test the engine, remove the tester and then the harness. Kentucky had automated this stage, there was only one different engine variant in US but Deeside has three.
Kentucky’s automated tester did a good job but it wasn’t 100% reliable. A cylinder was inserted into the connector but it was attached to another cylinder, and to another. “By the time this part had gone in and this part had come out, the assembly was varying hugely in space, which this was causing the reliability problem,” says Kenworthy.
“Our maintenance engineers engineered their own connectors and modified the machine with more accuracy in the connections. They worked with production members to reduce the variation when fitting the injectors.
The outcome: “Now both plants have an automated in-line tester based on an idea from a US plant which we’ve copied and improved, which the US guys have taken back. They have kaizened their own kaizen.”